Mounting sinusoidal fin elements in heat exchange envelope



P. HODSON ETI'AL MOUNTING SINUSOIDAL FIN ELEMENTS I Jan. 13', 1959 HEAT EXCHANGE ENVELOPE Orlglnal Filed March 50. 1950 www United States Patent G MOUNTING `SINUSOIDAL FIN ELEMENTS IN HEAT EXCHANGE ENVELOPE Peter Hodson and Sven Holm, Wellsville, N. Y.

1 Claim. (Cl. 257-245) The present invention relates to heat transfer apparatus and particularly to an improved form of extended or finned surface for exchange of heat between two confined fluids. This is a continuation of the Peter Hodson and Sven Holm U. S. application Serial No. 152,952, led March 30, 1950, now abandoned.

One well known form of heat exchanger for the transfer of heat between two confined fluids is made up of a plurality of spaced metallic plates forming passages through alternate ones of which a heating uid such as a hot gas flows in heat exchange relationship with the iluid to be heated, such as air, traversing the intermediate passages. The present invention contemplates providing the passage walls through which heat is exchanged with a myriad of pin-like ns and improvement in the heat transfer relationship between the fins and the walls of which they constitute extended surface by making the fins in the form of sinuously bent wires having U-shaped loops whose stretcher parts are seated in channels bonded to the passage walls. The invention will best be understood upon consideration of the following detailed description of illustrative embodiments thereof when read in conjunction with the accompanying drawings in which:

Figure 1 is a diagrammatic representation of a plate type heat exchanger in which the invention is embodied.

Figure 2 is a fragmentary sectional View of a plate type heat exchanger showing the manner in which the pin-like ns are applied to the passage forming walls in accordance with the present invention.

Figure 3 is a sectional view on the line 3 3 in Figure 2.

Figure 4 is a fragmentary view showing an alternative method of mounting the fins. n

Figures 5 to 9 are diagrammatic views illustrating how a good heat transfer relationship is maintained between the fin element and the mounting channels therefor despite defects in the manufacture or assembly of these parts; and

Figure is a fragmentary view showing the iin element directly secured to the plate.

Figure 1 diagrammatically shows a plate type heat exchanger in which the heating gas enters through the inlet 10 to ow longitudinally of the exchanger through alternate passages 11 (Fig. 2) formed between a plurality of spaced metallic plates 12 and 13. The air to be heated is supplied by a pair of inlet headers 14, 15 and flowing` into the manifolds 16 traverses the intermediate passages 18 leading to the outlet manifolds 20 and thence into the air outlet ducts 21 and 22. As shown in Fig. 2, pairs of plates 12 and 13 have the spaces therebetween along their side edges closed by closure strips 23 to form a unitary heat exchange envelope. Adjacent envelopes are spaced apart to define the air passages 18 whose sides are closed by spacer strips 25. On the air side extended surface is provided in the forms of strip fins 26 of channel section.

To increase the efliciency of heat transfer from the rif' ice y gas flowing in a passage 11, the walls 12 and 13 are provided with extended surface `in the form of a myriad of pin-like ns projecting in upright relation from the walls 12 and 13. Continuous lengths of p metallicmwire are bent substantially sinusoidally to form a tin element 30 having a plurality of U-shaped loops therein whose leg portions 31 constitute pin-like ns extending in upright relation between the plates 12, 13 while the stretcher portions 32 are alined along the axis of the wire and are, preferably, disposed in alinement in the general direction of gas flow. The stretcher portions 32 of a fin element 30 are seated in the grooves in a pair of channel members designated as a whole by the numeral 33. The stretcher parts 32 of an element 30 preferably contact both the `base portion 34 and the upright or leg parts 35 of these The leg parts 35 themselves alsoconstitute channels. extended surface on the passage walls 12, 13. In assembling a heat transfer envelope 36, Fig. 2, a pair of channel members 33 are iirst applied along opposite side edges of each sinuous element 30 with a strip of brazing foil intervening between the base 34 and inner faces of the legs 35 of the channel members and the stretcher portions 32 of the wire fin element. A series of fin elements 3d with channel members 33 assembledtherewith are then mounted between a pair of plates 12, 13 with other strips of brazing metal applied between the outer faces of the bases 34 of the channels 33 and the plates 12, 13. The spaces between the passage walls 12 and 13 at the sides are closed by the strips 23 which may be welded in place. The entire envelope assembly is then placed in a brazing oven and brazing bonds formed to transform the plates 12, 13 and tins 31 with channels 33 into an integral unit.

Figure 4 shows a form which the channel member is in the form of a spring clip 40 which tightly grasps the stretcher portions 32 of the sinuously formed iin element 30 and thus affords an efectiveheat transfer bond between the ns 31 and plates 12, 13.

lt may be seen in Fig. 5 that good heat transfer bonds lare maintained between the sinuous linned elements 30 and the channels 33, and hence with the heat transfer plates 12, 13 to which the latter are brazed, even though the sinuous wire element 30 may be distorted or sprung so that the stretcher portions 32 of some loops do not fcontact the base 34 of the channel element 33 because as illustrated here and in Fig. 7 a good heat transfer bond is provided by the large area of contact between the inner faces of the leg portions 35 of the channel 33 and stretchers 32 in the fin member 30. Figure 6 shows that even in cases where one or more loops in the sinuous fin element 30 have been incompletely formed, as being shortened, adequate contact is provided between the stretcher portion 32 of the misformed loop and the sidesv 35 of the channel member 33 to alford good heat transfer conditions. This is shown in Figure 7 also.

In Figs. 8` and 9 it is assumed that the passage wall 13 has been bowed so that it is no longer flat and hence is not in full planar Contact with the base 34 of the mounting channel 33 for a sinuous fin element 30. Nevertheless, in the brazng operation capillary attraction will cause some of the brazing metal to flow first into the areas A as indicated in Fig. 8 and, when these have been built up, further brazing metal will subsequently flow intothe area B as indicated in Fig. 9. Thus, despite bowing of the plate 13 a good heat transfer relationship is afforded between the passage wall plate 13 and the fins 31 which constitute extended surface thereof. This is to be contrasted with the conditions shown in Fig. 10 wherein it is assumed that the sinuous iin element is applied directly to a wall plate 13. Here the springing of the sinuous element, the misformation of a loop therein, `o1' bowing of the wall plate 13 would provide a gap between the plate and the stretcher portion 32 of the loop into which brazingrnetal would flow to form a llet C which however would not produce such good heat transfer relationship as i-s `aiorded by contact between the sides 34 of a channelr member 33 and the stretchers 32 of the sinuous tin elementv30 where the base 34 of the channel would be in proper heat transfer contact with the plate 13.

What we claim is:

.Inl a heat exchanger having metallic plates constituting walls of a fluid passage, and a plurality of heat exchange elements mounted in spaced relation in said passage parallel yto each other and the direction o-f fluid flow through the passage, each element consisting of an individual metallic Wire bent to substantially sinusoidal formy to provide a ribbon-like element formed of a plurality `of U-shaped loops lying .substantially in a common plane extending substantially perpendicular to said plates, each loop having legs and a base, the bases of said loops forming the edges of said ribbon-like element; the improvement comprising a metallic channel member with base and anges at angles thereto, said flanges being 4 spaced apart approximately the thickness of said Wire and ribbon-like element and extending along and parallel to the major axis of the ribbon-like element with bases of the loops iitting closely into said channel member and with the side faces of theribbon-like element in contact with the anges of the channel member and an edge of the ribbon-like element contacting the base of the channel member at intervals along a line parallel to the axis of the channel; and metallic joints permanently joining the anges and faces of said channel to the side faces and Heier-ences Cited in the le of this patent UNITED STATES PATENTS Grimes J-uly 23, Y1929 2,330,549 Bowers Sept. 28, 1943 2,645,462 Holm July 14, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,868,514 January 13, 1959 Peter Hodson and Sven Holm It is hereby certified that error appears in the above numbered patent requiringv correction and that the said Letters Patent should read as corre-cte'd below.

In the grant, lines l, 2 and 3, for "Peter Hodsonv and Sven Holm, o Wellsville, New York," read Peter Hodson and Sven Holm, of Wellsville, New York, assignors to The Air Preheater Corporation, of NewYork, N. Y. line l2, for Peter Hodson and Sven Holm, their heirsH read The Air Preheater Corporation, its successors in the heading to the printed specification, li-ne 4, for HPeter Hodson and Sven Holm, Wellsville, N. Y." read Peter Hodson and Sven Holm, Wellsville, N. Y. assignorsl to The Air Preheater Corporation, New York, N. `l.

Signed and sealed this 28th day of July 19.59.

(SEAL) l Attest: l I

KARL H, AXLINE ROBERT c. WATSON l .At-testing officer comissioner of Patents l 

